Methods of Fitting and Retrofitting Transformers with Fault Indicators, and Fault Indicators Therefor

ABSTRACT

Fault-indicator assemblies that can each be mounted externally to a corresponding electronic device to provide a visual indication that an internal fault has occurred within the electronic device. A fault-indicator assembly of the present disclosure can be configured for electrical devices such as electrical power transformers, capacitors, and reactors, among others. Some embodiments can be configured to connect to existing orifices of a conventionally manufactured electronic device, such as an orifice for a conventional pressure-relief valve. Such embodiments can be deployed without any modifications to the electrical devices and can be readily retrofitted to existing electrical devices. In some embodiments, a pressure-relief valve can be integrated with the fault-indicator assembly to provide both fault-indication functionality and pressure-relief functionality in the same assembly.

RELATED APPLICATION DATA

This application is a continuation of U.S. patent application Ser. No.16/434,933, filed Jun 7, 2019, entitled “Externally Mountable FaultIndicator Assemblies for Electrical Devices, Systems Incorporating Same,and Methods of Using Same”, which application was a continuation of U.S.patent application Ser. No. 16/177,953, filed Nov. 1, 2018, now U.S.Pat. No. 10,345,367, granted Jul. 9, 2019. Each of these applications isincorporated herein by reference in its entirety.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to the field of electricaldevice fault indicators. In particular, the present disclosure isdirected to externally mountable fault indicator assemblies forelectrical devices, systems incorporating same, and methods of usingsame.

BACKGROUND

Electrical power distribution grids use electrical devices, such astransformers, capacitors and reactors to control the power on thenetwork. Dangerous conditions can be created in such electrical deviceswhen aging or operating stresses cause the insulation system to fail. Ashort circuit within such an electrical device can release a largeamount of energy within a fraction of a second. In the worst case, theelectrical device can explode due to rapid pressure surges from thevaporizing of the insulating oil and the decomposition of the oil vaporinto combustible gases. Some electrical devices are filled withelectrically insulating gases such as sulfur hexafluoride. In suchgas-filled devices arcing can cause pressure surges in the gas.

Unfortunately, an internal fault within an electrical device may occurwithout providing a visible sign to the outside. Unless servicepersonnel can tell that a particular device has failed, they mayre-apply power to the device without detecting that a failure hasoccurred, exposing them to the significant risk that the electricaldevice could explode when reenergized and the fault reoccurs andgenerates a high internal pressure.

SUMMARY OF THE DISCLOSURE

In an implementation, the present disclosure is directed to a method offitting an electrical transformer with a fault indicator that indicateswhen the electrical transformer has experienced a fault that causes aninternal pressure increase within an interior space of the electricaltransformer, wherein the electrical transformer has a preexistingpressure-relief-valve port designed and configured to receive aconventional pressure-relief valve. The method includes providing afault-indicator assembly comprising a pressure-relieve valve; apressure-activated actuator operatively coupled to an onboard visualindicator or a communication trigger, or both an onboard visualindicator and a communication trigger, wherein the fault-indicatorassembly is provided to sense when the internal pressure has increasedin a manner characteristic of a fault occurring with the electricaltransformer; and a fitting designed and configured to engage thepreexisting pressure-relief-valve port; and securing the fault-indicatorassembly to the electrical transformer, wherein the securing includesengaging the fitting of the fault-indicator assembly with thepreexisting pressure-relief-valve port.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the disclosure, the drawings showaspects of one or more embodiments of the disclosure. However, it shouldbe understood that the present disclosure is not limited to the precisearrangements and instrumentalities shown in the drawings, wherein:

FIG. 1 is a schematic diagram of a fault-indicator assembly made inaccordance with the present disclosure;

FIG. 2 is a partial elevational view of a pair of pole-mounted stepdowntransformers that each include an externally mounted fault-indicatorassembly made in accordance with the present disclosure;

FIG. 3A is a side elevational view of an example instantiation of afault-indicator assembly made in accordance with the present disclosure,showing the visual indicator in a non-fault-indicating position;

FIG. 3B is a side elevational view of the fault-indicator assembly ofFIG. 3A, showing the visual indicator in a fault-indicating position;

FIG. 4 is a side elevational view of the fault-indicator assembly ofFIGS. 3A and 3B, showing a part of the housing removed to revealinterior components;

FIG. 5 is an enlarged view of a portion of the side elevational view ofFIG. 4;

FIG. 6 is a graph of measured pressure and voltage over time duringtesting of the fault-indicator assembly of FIGS. 3A to 5;

FIG. 7 is a high-level schematic diagram illustrating a fault-indicatorassembly of the present disclosure configured to communicate with aremote notification system; and

FIG. 8 is a high-level schematic diagram illustrating a computing systemthat can be incorporated into the notification system of FIG. 7.

DETAILED DESCRIPTION

In some aspects, the present disclosure is directed to a fault-indicatorassembly that indicates when an electrical device has experienced aninternal fault that manifests itself as an abnormal pressure rise withinthe electrical device. Such a fault-indicator assembly is particularlyuseful for oil-filled and gas-filled electrical devices, such astransformers, capacitors, and reactors, used on power-distributionnetworks and the like. A fault-indicator assembly of the presentdisclosure provides a visual indication that the internal pressure ofthe electrical device has reached a predetermined level indicative of aninternal fault having occurred. An example of an internal fault that cancause a relatively high pressure inside an oil-filled electrical deviceis an internal arcing fault that produces a large temperature increasethat vaporizes some of the oil. In a gas-filled electrical device, suchas an electrical device filled with electrically insulating sulphurhexafluoride, internal arcing causes pressure surging within the gas.

Referring to the accompanying drawings, FIG. 1 illustrates an examplefault-indicator assembly 100 of the present disclosure locatedexternally to, and fluidly connected to, an electrical device 104, whichmay be any electrical device, such as a transformer, capacitor, orreactor, filled with an insulating fluid, for example, oil or gas.Electrical device 104 includes an interior space 104A that containsvarious internal components 104B, including but not limited toelectrical windings and/or other electrical conductors and insulation,such as insulation paper and/or insulation boards, among other things.Those skilled in the art will be familiar with the components that makeup internal components 104B of electrical device 104, depending on thetype of the electrical device.

In this example, fault-indicator assembly 100 includes a visualindicator 108 that is controlled by a pressure-activated actuator 112via an actuation coupling 116. Pressure-activated actuator 112 isfluidly coupled to interior space 104A of electrical device 104 via aconnecting structure 120, as indicated by arrows 124(1) and 124(2) thatdenote conveyance of pressure from, respectively, the internal space tothe connecting structure and from the connecting structure to thepressure-activated actuator. Consequently, when pressure changes withininterior space 104A, both connecting structure 120 andpressure-activated actuator 112 also experience a pressure change.Depending on the magnitude of the pressure within interior space 104Aand experienced by pressure-activated actuator 112, thepressure-activated actuator controls the visual-indication state ofvisual indicator 108.

Visual indicator 108 and pressure-activated actuator 112 are selectedand designed in conjunction with one another so that fault-indicatorassembly 100 provides persistent fault-indicating functionality thatsignals that a triggering pressure level has occurred even when thepressure has subsequently decreased below the triggering pressure level.In this example, visual indicator 108 may be considered to have twostates—a non-fault-indicating state and a fault-indicating state—andthese states may take any of a variety forms. For example, in someembodiments, the non-fault-indicating and fault indicating states may bebased on one or more illumination sources, such as one or morelight-emitting diodes. In one example that uses a pair of illuminationsources, the non-fault-indicating state may be one of the illuminationsources emitting green light and the fault-indicating state may be theother of the illumination sources emitting red light. In another exampleusing a single illumination source, the non-fault-indicating state maybe the illumination source not emitting any light and thefault-indicating state may be the illumination source emitting redlight. In each of these examples, pressure-activated actuator 112 may bea pressure transducer that generates electrical non-fault and faultsignals for controlling the illumination of the illumination source(s).Such a pressure transducer may be based on any suitablepressure-activate device, such as a bellows (see detailed examplebelow), a Bourdon tube, or a diaphragm, among others. Visual indicator108 and/or pressure-activated actuator 112 may be configured so thateven when the pressure that caused the visual indicator to change to thefault-indicating state reduces or is reduced, the visual indicationremains in the fault-indicating state. This allows an observer to knowthat electrical device 104 may be damaged and require fixing orreplacement before reenergizing. In these examples, actuation coupling116 comprises the electrical signals for illuminating the illuminationsource(s).

In some embodiments, visual indicator 108 may be a mechanical device forwhich the non-fault-indicating and fault-indicating states correspond todiffering positions of one or more movable members of the mechanicaldevice. For example, the mechanical device may be a dial-gage-likedevice having a movable needle that is movable between anon-fault-indicating position and a fault-indicating position. In thisexample, the needle may be moved by a Bourdon tube (i.e.,pressure-activated actuator 112) as pressure within the Bourdon tubeincreases. The dial-gage-like device may have a dial marked with a redzone, and if the needle is in the red zone, an observer would know thatelectrical device may be damaged. In this example, the needle moves inonly one direction—toward and/or into the red zone—by virtue of theBourdon tube only being able to push the needle to move it. Thisprovides the persistent indication that a fault-level pressure occurredeven though the pressure may have subsequently reduced to a normallevel. The needle may be secured to a pivot so as to have enoughfriction with the pivot to remain in the position the Bourdon tube haspushed it to after the Bourdon tube has relaxed. This dial-gage-likedevice may be in the form of a rotary dial or a linear dial and may havea moveable member other than a needle. This sort of device may beconsidered non-binary, since the movable member can be moved with anypressure increase, and not just pressure increases that move the movablemember into the red zone. In this example, actuation coupling 116comprises the engagement of the Bourdon tube with the movable member.

Another example of a mechanical device that can be used for visualindicator 108 is a plunger-style device having a plunger-like elongatebody that is longitudinally movable between a non-fault-indicatingposition (a/k/a state) and a fault-indicating position (a/k/a state)within a corresponding receiver. In one example, the operation of theelongate body is binary in nature, with the non-fault-indicatingposition being a position in which the elongate body is fully retractedinto the receiver and the fault-indicating position being a position inwhich the elongate body fully extended out of the receiver. An exampleof a plunger-style version of visual indicator 108 is described below indetail in conjunction with FIGS. 3A to 5. In some embodiments, theelongate body may be held in the non-fault-indicating position by acatch while being biased, for example, by one or more springs, one ormore elastic bands, gravity (e.g., with a downwardly moving elongatebody), etc., toward the fault-indicating position. In such embodiments,a trigger actuated by pressure-activated actuator 112 causes the catchto release, which in turn allows the elongate body to move underinfluence of the biasing. In these embodiments, pressure-activatedactuator 112 may be of any suitable type, such as a deformable type thatdeforms either continuously with changing pressure or suddenly when thepressure reaches a trigger pressure. This deformation moves the trigger,which in turn releases the catch and allows the elongate body to moveunder influence of the biasing. It is noted that the trigger may be aseparate member or structure relative to pressure-activated actuator 112and the catch. However, it could also be integrated into either thepressure-activated actuator 112 or the catch. For example, the triggermay simply be a protrusion or other structure on the catch thatpressure-activated actuator contacts directly to release the catch. Inthis example, actuation coupling 116 comprises the trigger andcorresponding catch. Other embodiments are certainly possible.

In another example of a plunger-style visual indicator 108, the elongatebody may be held in the non-fault indicating position by friction, forexample, with a sleeve or O-ring seal located between the end of ahousing near the end of the elongate body that extends from the housingwhen the visual indicator has been triggered. In this example, theelongate body may be pushed from the non-fault indicating position tothe fault-indicating position by a diaphragm moved by a differentialpressure between interior space 104A of electrical device 104 andambient pressure outside of the electrical device. Such diaphragm mayact against a spring calibrated to the appropriate pressures. In thisexample, once the diaphragm has pushed the plunger-type visual indicator108 to the extended fault-indicating position, it remains in thatposition by virtue of the friction noted above even though the diaphragmmay have retracted because of subsequent reduction of pressure withininterior space 104A of electrical device.

Connecting structure 120 allows fault-indicator assembly 100 to belocated externally to electrical device 104 and provides a fluidpassageway between interior space 104A of the electrical device andpressure-activated actuator 112, for example, via an orifice 104C. In asimple form, connecting structure 120 may be a rigid or flexible conduitthat provides the fluid passageway. In an even simpler form, connectingstructure 120 may consist essentially of a connection fitting that makesa direct fluid connection of pressure-activated actuator 112 toelectrical device 104. If connecting structure 120 includes an elongateconduit, pressure-activated actuator 112 may be located at leastsomewhat distally from electrical device 104 or in a location spacedfrom orifice 104C, if desired. For example, if orifice 104C is locatedwhere insufficient clearance exists to locate pressure-activatedactuator 112 there, or where an observer could not readily view visualindicator 108, then providing connecting structure 120 with asufficiently long conduit would allow pressure-activated actuator 112and visual indicator 108 to be located remotely from orifice 104C.

In one example, orifice 104C is threaded. In this example, connectingstructure 120 can have a threaded end threaded to threadedly engagethreaded orifice 104C so that the connecting structure can be connectedto electrical device 104. It is noted that some electrical devices, suchas transformers, are currently manufactured with pressure-relief-valveorifices that receive corresponding respective conventionalpressure-relief valves. Consequently, in some embodiments, the end ofconnecting structure 120 may be adapted for these specific conventionalorifices.

In this connection, connecting structure 120 may itself optionallyinclude, or otherwise fluidly communicate with, a pressure-relief valve128. In embodiments of fault-indicator assembly 100 adapted to engage aconventional pressure-relief-valve orifice, pressure-relief valve 128replaces a conventional pressure-relief valve. This allows existing andconventionally manufactured electrical devices having such orifices tobe easily retrofitted with external fault-indicator assemblies made inaccordance with the present disclosure. This is in stark contrast withconventional fault indicators that require pressure-sensing componentsto be located within the interior space of the electrical device.Consequently, conventional fault indicators are not readily retrofittedinto existing and conventionally manufactured electrical devices.

FIG. 2 illustrates a pair of fault-indicator assemblies 200(1) and200(2) deployed on the exteriors of corresponding respective electricaltransformers 204(1) and 204(2). In this example, each fault-indicatorassembly 200(1), 200(2) may be identical to fault-indicator assembly 100of FIG. 1. In this example, transformers 204(1) and 204(2) are mountedto a utility pole 208 and deployed as three-phase stepdown transformersthat stepdown the voltage on higher-voltage lines 212(1) to 212(3) toprovide lower-voltage lines 216(1) to 216(3) with a lower voltage. Asnoted above, electrical transformers, here electrical transformers204(1) and 204(2), are just one example of electrical devices that canbenefit from fault-indicator assemblies of the present disclosure.

Example Fault-Indicator Assembly

FIGS. 3A to 5 illustrate a fault-indicator assembly 300 that is aspecific instantiation of fault-indicator assembly 100 depicted inFIG. 1. Referring first to FIG. 3A, fault-indicator assembly 300includes a visual indicator 304 and a connecting structure 308 that hasa connection end 308A in the form of a connection fitting 308B. In thisexample, connection fitting 308B is a threaded fitting particularlyconfigured to threadingly engage a mating threaded orifice (not shown)in a wall of an electrical device (not shown). Fault-indicator assembly300 also includes an integrated pressure-relief valve 308C, which, here,is integrated with connecting structure 308. Visual indicator 304comprises an elongate body 304A slidably engaged within a correspondingreceiver 312 provided within a housing 316. FIG. 3A shows visualindicator 304 fully retracted into elongate body receiver 312, with onlya headed end 304B showing on the outside of fault-indicator assembly300. This fully retracted position of visual indicator 304 is thenon-fault-indicating position 320 (a/k/a state) of the visual indicator.In this example, visual indicator 304 remains in non-fault-indicatingposition 320 as long as the pressure within an interior region of anelectrical device (not shown) on which fault-indicator assembly 300 isdeployed does not cause the pressure within the fault-indicator assemblyto equal or exceed a predetermined triggering pressure of thefault-indicator assembly.

FIG. 3B, on the other hand, shows visual indicator 304 fully extendedfrom receiver 312 along a longitudinal axis 322, revealing to anobserver a previously concealed portion 304C of the visual indicator.This fully extended position of visual indicator 304 is thefault-indicating position 324 (a/k/a state) of the visual indicator. Asdescribed below in detail, visual indicator 304 changes position fromnon-fault-indicating position 320 to fault-indicating position 324 basedon the pressure within the interior space of the electrical device (notshown) causing the pressure within fault-indicator assembly 300 to equalor exceed the predetermined triggering pressure of the fault-indicatorassembly. Once visual indicator 304 is in fault-indicating position 324,it remains in this position even if the pressure within fault-indicatorassembly 300 falls below the predetermined triggering pressure. Thisallows an observer to see that the electrical device (not shown) hasexperienced an elevated internal pressure indicative of a fault havingoccurred, regardless of how long it has been since the fault occurredand regardless of the current pressure within the electrical device.Seeing visual indicator 304 in its fault-indicating position 324 is asignal to an observer that the electrical device should not bereenergized before it is inspected, repaired, and/or replaced. Whilevisual indicator 304 provides visual indication of an internal faultwithin the electrical device merely by virtue of its extension fromreceiver 312, in some embodiments previously concealed portion 304C canbe colored or otherwise marked to make observation easy. For example,previously concealed portion 304C can be colored red, yellow, orange, orother bright color so that visual indicator is easily viewable. In someembodiments, a user can reset fault-indicator assembly 300 by pushingvisual indicator 304 back into receiver 312 when the pressure within thefault-indicator assembly is suitably low.

In this example, housing 316 contains not only receiver 312 but also apressure-activated actuator 328 (see FIG. 4) and a portion of connectingstructure 308, among other things. In this manner, housing 316effectively makes fault-indicator assembly 300, includingpressure-relief valve 308C, into a robust unitary device. Housing 316may be made of any suitable material(s), such as plastic,fiber-reinforced composite, and/or metal, among others. As seen whenviewing either of FIGS. 3A and 3B in conjunction with FIG. 4, housing316 in this example is a two-part housing comprising a first half 316A(FIGS. 3A and 3B) and a second half 316B (FIG. 4) that are joinedtogether via fasteners (not shown) that extend through fastener openings332 (FIG. 4) on the second half and into corresponding receivers (notshown) on the first half to join the two halves to one another.

FIG. 4 shows components of fault-indicator assembly 300 of FIGS. 3A and3B located within housing 316. Referring to FIG. 4, in this examplepressure-activated actuator 328 has an expandable body 328A, here, abellows, having an interior (not shown) that is fluidly coupled to theinterior space (not shown) of an electrical device through connectingstructure 308 and therefore is subjected to effectively the samepressure that is in the interior space. The pressure differentialbetween the interior of expandable body 328A and the space 336 withinhousing 316 in which the expandable body is located causes theexpandable body to expand or contract depending on the pressuredifferential between the two spaces. Not seen in FIG. 4 is the fluidpassageway internal to connecting structure 308 that fluidly connectsboth the interior of expandable body 328A and pressure-relief valve 308Cto the interior space (not shown) of an electrical device whenfault-indicator assembly 300 is connected to the electrical device viaconnecting structure 308.

Referring to FIGS. 4 and 5, in this example, when the pressure withinexpandable body 328A is suitably low, visual indicator 304 is held inits non-fault-indicating position 320 (also FIG. 3A) by a catch 340,here, a shear pin that extends through an aperture 316C (FIG. 5) in wall316D (FIG. 5) of housing 316 and into a receiver 304D (FIG. 5) withinthe visual indicator. Visual indicator 304 is biased in a directiontoward fault-indicating position 324 (FIG. 3B) by a biasing means 344,here a single helical spring compressed between housing 316 and visualindicator 304. More than one spring can be used. Biasing means 344 neednot be a helical spring, but rather could be, among other things anothertype of spring, another type of resilient member (e.g., elastomericmember), or gravity. Gravity can be used as biasing means 344 if, forexample, fault indication assembly 300 is mounted so that visualindicator 304 moves vertically downward from its non-fault-indicatingposition 320 to its fault-indicating position 324 (i.e., when thefault-indicator assembly is rotated 90° clockwise relative to theorientation shown in FIGS. 3A to 5). It is noted that catch 340 need notnecessarily be a shear pin, and can alternatively be any other suitablestructure that releasably holds visual indicator 304 and/or biasingmeans 344.

As best seen in FIG. 5, the shear pin (i.e., catch 340) is biased towardaperture 316C by a biasing means 348, here a helical spring. Anothertype of biasing means can be used for biasing means 348, including anyof the biasing means noted above for biasing means 344. When catch 340is in registration with aperture 316C and the pressure within expandablebody 328A is suitably low, biasing means 348 urges the catch into theaperture, thereby allowing the catch to act as a shear pin betweenvisual indicator 304 and wall 316D so as to hold the visual indicator inits non-fault-indicating position 320.

As also best seen in FIG. 5, in this example fault-indicator assembly300 includes a trigger 352 coupled to and moved by expandable body 328A.As expandable body 328A expands upwardly (relative to FIG. 5), it movestrigger 352 upward, which in turn pushes catch 340 upward. When thepressure within expandable body 328A is great enough and thereforeexpands enough, the contacting end surfaces of catch 340 and trigger352, respectively, align horizontally (relative to FIG. 5) with thesliding interface between end 304E of visual indicator 304 and interiorsurface 316E of wall 316D. When this alignment occurs, catch 340 isdisengaged from aperture 316C and therefore releases visual indicator304, and biasing means 344 urges the visual indicator to itsfault-indication position 324 (FIG. 3B). In this example, end 304E ofvisual indicator 304 has a shoulder 304F that engages an end wall 316Fof housing 316 to keep biasing means 344 from pushing the visualindicator out of receiver 312. Also in the example, trigger 352 includesa threaded shaft 352A and a threaded adjuster 352B that allows a user toadjust the pressure at which catch 340 is released. Screwing threadedadjustor 352B farther onto threaded shaft 352A results in trigger 352releasing catch 340 at a higher pressure, and screwing the threadedadjustor in the opposite direction results in the trigger releasing thecatch at a lower pressure. In one instantiation in which expandable body328A was a bellows having an equilibrium volume of 9.01 cm³, the bellowswas configured so that it deformed under pressure as illustrated in thefollowing Table I.

TABLE I Pressure Displacement (psi) (mm) 4.5 1.12 6.0 2.34 8.0 4.14 9.04.79

Regarding triggering pressure, for many oil-filled transformers used forpower distribution, conventional pressure-relief valves are typicallyset to trigger at 10 psi. For these applications, pressure-relief valve308C (FIGS. 3A to 4) may be similarly configured to trigger at 10 psi.In such an application, fault-indicator assembly 300 is connected to atransformer so that expandable body 328 is in fluid communication withthe gas space above the oil level within the interior space of thetransformer.

In one example of a wide calibration, expandable body 328 and threadedadjustor 352B are configured and adjusted to trigger catch 340 torelease visual indicator 304 at 9 psi, which is before pressure-reliefvalve 308C starts releasing pressure at 10 psi. In this manner,fault-indicator assembly 300 can detect slow and accumulative pressureincrease caused by low energy arcs (partial discharge failure mode ofthe transformer).

In an example of a reduced calibration, expandable body 328A andthreaded adjustor 352B are configured and adjusted to trigger catch 340to release visual indicator 304 at 11 psi, which is afterpressure-relief valve 308C starts releasing pressure at 10 psi. At thispressure, pressure-relief valve 308C is already releasing pressure andfault-indicator assembly will need a pressure increase rate higher thanthe releasing pressure rate of the pressure-relief valve. This wastested in a laboratory, and it was found that a pressure rate of 3psi/sec can be enough to trigger release of visual indicator 304 even ifpressure-relief valve 308C is already releasing pressure. It is notedthat the pressure rate may be different from 3 psi/sec ifpressure-relief valve 308C is sized differently. However, IEEE standardsrequire pressure-relief valve 308C to operate at 10 psi and a flow rateof 35 scfm, so a different pressure rate may not be needed. A reason forusing the reduced calibration is to avoid a false operation in the casethat the pressure increases due to temperature increase when theelectrical device is overloaded (e.g., by oil expansion). This can causethe pressure to rise up to 9 psi. It is noted that the triggeringpressure can be set to be equal to the release pressure ofpressure-relief valve 308C, if desired.

Experimental Testing Testing Procedure—Low-Energy Test

An instantiation of fault-indicator assembly 300 of FIGS. 3A to 5 wasmounted to a testing tank. A high-voltage transformer terminal wasconnected to a vertical electrode and ground was connected to ahorizontal electrode. Then, an oil mixer was turned on. The transformerwas energized and the voltage was regulated to a level of 5 kV toproduce low energy arcing (approx. 1 Ampere) during a period of 10seconds. The voltage was lowered and the transformer was de-energized.The procedure was repeated with consecutive cycles until the pressurewas sufficient enough to trigger visual indicator 304 of fault-indicatorassembly 300 and to operate pressure relief valve 308C, which was set to10 psi. The pressure values were measured, recorded, and plotted duringthe test. FIG. 6 shows the pressure values, via pressure curve 600,measured over time during the test. Curve 604 displays the voltage overtime during the test. In this test, the pressure rose approximately0.053 psi/min. Pressure curve 600 shows, that the pressure graduallyincreased, simulating a high-impedance internal fault, such as a lowenergy partial arcing inside the transformer. Fault-indicator assembly300 triggered visual indicator 304 at the calibration pressure of 9.5psi, illustrated at point 608. This result demonstrates thatfault-indicator assembly 300 is sensitive enough to detect this failuremode. Relief-valve operation triggered at a pressure of approximately10.03 psi, as indicated at point 612.

High-Energy Tests

It is recognized that the test conditions that could simulate ahigh-energy arc inside a transformer should ultimately be described interms of the energy applied, with the pressure wave defined by the rateof rise, length of the arc, peak pressure, duration, and total energyunder the curve. In order to simulate a high-energy arc inside atransformer to perform the fault indicator tests, the test proceduredescribed in IEEE Standard C57.12.20, Section 9 was used. This testprocedure is not intended to include all possible conditions that mayoccur in service under fault conditions, but rather to establish ameaningful test that is repeatable and capable of duplication in variouslaboratories and test situations.

A simulated internal fault was provided for the test. This simulatedfault consisted of a 25 mm (˜1 in) arc gap mounted horizontally andlocated 25.4 mm (1 in) above core clamps. This gap was bridged initiallyby a copper wire that had a diameter smaller than 1.0 mm (0.0394 in or18 AWG). The gap was connected between the high-voltage terminals. Themounting blocks or terminals of the gap consisted of copper-bearingmaterial having flat surfaces from 6 mm to 20 mm (0.25 in to 0.75 in) indiameter or in width. These mounting blocks or terminals were designedto maintain this 25 mm (˜1 in) arc gap for the duration of the testing.A transformer coil was not electrically connected in this test circuit.The power source was 7.2 kV and adjusted to supply the desired arccurrent. The above-identified Standard defines an arc current of 8000 A.However, various tests were performed at lower current values to findthe sensitivity of fault-indicator assembly 300.

During the tests, fault-indicator assembly 300 was able to reliablytrigger visual indicator 304 and signal the presence of an internalfault in a pole mounted distribution transformer. The test resultsvalidate that fault-indicator assembly 300 triggers visual indicator 304and signals the presence of internal faults with currents as low as theones shown in Table II below.

TABLE II Applied Currents for High-Energy Tests Applied Current Testduration (A) (mS)  472 66.6 1024 33.3 1776 33.3 8000 33.3 (IEEE StandardTest)

Example Fault-Indicator Assembly Having Remote CommunicationFunctionality

FIG. 7 illustrates an example fault-indicator assembly 700 that is ableto communicate to a remotely located notification system 704 that thepressure inside an electrical device 708 has reached a level indicativeof an internal fault having occurred within the electrical device. Asnoted above, both fault-indicator assembly 700 and electrical device 708may be, respectively, the same as and/or incorporate the same or similarfeatures as any of the fault-indicator assemblies and electrical devicesdescribed above.

In this example, fault-indicator assembly 700 includes apressure-activated actuator (PAA) 712 that has the same or similarfunctions as described above relative to pressure-activated actuator 112of FIG. 1 and can likewise be any suitable actuator or sensor responsiveto pressure changes within the interior space of electrical device 708.In this example, pressure-activated actuator 712 of FIG. 7 causes,either directly or indirectly, a communication trigger 716 to send oneor more signals 720 to a communication module 724 that cause thecommunication module to transmit a notification signal 728 tonotification system 704 via one or more communication networks 732. Asdescribed below in more detail, notification signal 728 allowsnotification system 704 to notify one or more human users (not shown)and/or one or more external systems (not shown) that fault-indicationassembly 700 has been triggered such that an internal fault may haveoccurred within electrical device 708.

Communication trigger 716 may be any suitable device or system that cangenerate signal(s) 720 for communication module 724 when fault-indicatorassembly 700 has reached its triggering pressure based on pressurewithin internal space of electronic device 708. In one example, ifpressure-activated actuator 712 comprises an electronic pressure sensor,then communication trigger 716 may comprise circuitry within, or incommunication with, the electronic pressure sensor that generatessignal(s) 720 when the electronic pressure sensor has reached thetriggering pressure. As another example, if pressure-activated actuator712 comprises a deformable component that deforms with changingpressure, such as occurs with a bellows, Bourdon tube, etc., thecommunication trigger 716 may comprise a switch that is actuated to sendsignal(s) 720 by movement of the deformable component. In the context offault-indicator assembly 300 of FIGS. 3A to 5, when the triggeringpressure is reached, expandable body 328A may push against aspring-loaded switch (not shown) that causes signal(s) 720 (FIG. 7) tobe communicated to communication module 724. As another example in whichpressure-activated actuator 712 comprises a deformable body,fault-indicator assembly 700 may be provided with a position sensor thatcan identify when the position of a portion of the deformable body movesto a position corresponding to the triggering pressure. Such a positionsensor can be of any suitable type, such as mechanical, light-basedand/or piezoelectric, among others.

In some embodiments, fault-indicator assembly 700 may optionally includea visual indicator 736, which can be the same as or similar to any oneor more of the visual indicators described above relative to FIGS. 1 to5. When visual indicator 736 is present and is of a movable type, suchas visual indicator 304 of FIGS. 3A to 5 or the movable visualindicators described above relative to visual indicator 108 of FIG. 1,communication trigger 716, similar to the situation just describedrelative to a deformable body type of pressure-activated actuator 712,may be a switch or other type of position sensor that senses when thevisual indicator is in its fault-indicating position. For example,fault-indicator assembly 300 of FIGS. 3A to 5 may be enhanced with aswitch located on the inside of end wall 316F (FIG. 5) such that whenvisual indicator 304 has been triggered and shoulder 304F of end 304E ofthe visual indicator is moving toward end wall 316F of housing 316, theshoulder impacts upon the switch, thereby activating it. Many otheralternatives are possible. In addition, depending on the configurationsand presence of any trigger and catch, such as trigger 352 and catch 340of FIG. 5, either or both of those may be used for triggeringcommunication trigger 716. In this case, communication trigger 716 maybe, for example, a switch or other position sensor responsive to theposition of either the trigger or catch, or both.

Fault-indicator assembly 700 of FIG. 7 may optionally include apressure-relief valve (PRV) 736. Pressure-relieve valve 736 may be thesame as or similar to any of the pressure-relief valves described above,such as pressure-relief valve 128 of FIG. 1 and pressure-relief valve308C of FIGS. 3A to 5. Pressure-relief valve 736 may be configured toadditionally or alternatively cause communication trigger 716 to sendsignal(s) to communication module 724.

Communication module 724 may be any suitable wired or wirelesscommunications device, such as a wireless radio-frequency transmitter ortransceiver (e.g., a transmitter or transceiver that transmits using anIEEE 802.11 protocol), an optical transmitter or transceiver (e.g., atransmitter or receiver that transmits either in open air or via anoptical fiber), or a wired transmitter or transceiver that transmitsanalog or digital signals over a communication cable, among others.Fundamentally, there are no limitations on the type of communicationmodule 724 and the communication protocol used, as long as they arecompatible with communication network(s) 732.

Communication network(s) 732 may be composed of any one or more networksthat can carry notification signal 728 from communication module 724 toa communication module 740 of notification system 704. Examples of suchcommunication networks include, but are not limited to, local-areanetworks, wide-area networks, global networks (e.g., the Internet),cellular communication networks, microwave communication networks,radio-frequency networks, optical communication networks, electricalpower networks, and/or wired telephone communication networks, amongmany others. Fundamentally, there are no limitations on the type andnumber of networks that can compose communication network 732 other thanit/they can communicate notification signal 728 from communicationmodule 724 of fault-indicator assembly 700 to communication module 740of notification system 704.

In addition to communication module 740 that receives notificationsignal 728, notification system 704 may include one or more processors(collectively represented at processor 744), one or more memories(collectively represented as memory 748), one or more displays(collectively represented as display 752), and one or more communicationports (collectively represented as communication port 756), among otherthings. Memory 748 is in operative communication with processor 744 andcontaining machine-executable instructions (not shown) for, among otherthings, executing algorithms and associated tasks for carrying out thefunctionalities described herein. Those skilled in the art will readilyunderstand how to embody such algorithms based on the present functionaldescriptions such that further explanation is not required for thoseskilled in the art to understand how to execute all aspects of thisdisclosure.

Processor 744 may comprise any one or more processing devices, such asone or more microcontrollers, one or more central processing units, oneor more processing cores of a system on a chip, one or more processingcores of an application specific integrated circuit, and/or one or morefield programmable gate arrays, among others. Memory 748 can be anytype(s) of suitable machine memory, such as cache, RAM, ROM, PROM,EPROM, and/or EEPROM, among others. Machine memory can also be anothertype of machine memory, such as a static or removable storage disk,static or removable solid-state memory, and/or any other type ofpersistent hardware-based memory. Fundamentally, there is no limitationon the type(s) of memory other than it be embodied in hardware. Themachine-executable instructions compose software (e.g., firmware and/orapplication(s) or portion(s) thereof) that controls many aspects ofnotification system 704. In some embodiments, notification system 704 orportions thereof can be executed in a general computing system, anexample of which is described below in connection with FIG. 8.

Referring still to FIG. 7, display 752 may be any suitable displayobservable or otherwise perceivable by a human operator, including butnot limited to a graphical display, another type of visual display(e.g., one or more lights, dials, etc.), an aural display, and/or ahaptic display, among others. When fault-indicating assembly 700 hasbeen triggered, communication module 724 has sent notification signal728, and communication module 740 has received the notification signal,processor 744 executes suitable software to cause display to display anotification that one or more observers can perceive so as to indicateto the observer(s) that the fault-indicating assembly has been triggeredso as to alert the observer(s) that electrical device 108 may haveexperienced an internal fault. Similarly, when communication module 740receives notification signal 728, processor 744 may also oralternatively execute suitable software that sends a suitable faultsignal to one or more external systems (not shown) that are eachconfigured to respond to the fault signal in a useful manner. Examplesof such external systems include but are not limited to,power-distribution control systems, system-wide alert systems, broadcastalert systems, and network-wide fault-tracking systems, and criticalevent management systems, among others.

Example Computing System

It is to be noted that any one or more of the aspects and embodiments ofnotification system 704 of FIG. 7 described herein may be convenientlyimplemented in and/or using one or more machines (e.g., one or morecomputers, one or more communications network devices, one or moreelectrical distribution network devices, any combination and/or networkthereof, among other things) programmed according to the teachings ofthe present specification, as will be apparent to those of ordinaryskill in the computer arts. Appropriate software coding can readily beprepared by skilled programmers based on the teachings of the presentdisclosure, as will be apparent to those of ordinary skill in thesoftware art. Aspects and implementations discussed above employingsoftware and/or software modules may also include appropriate hardwarefor assisting in the implementation of the machine executableinstructions of the software and/or software module.

Such software may be a computer program product that employs amachine-readable storage medium. A machine-readable storage medium maybe any medium that is capable of storing and/or encoding a sequence ofinstructions for execution by a machine (e.g., a computing device) andthat causes the machine to perform any one of the methodologies and/orembodiments described herein. Examples of a machine-readable storagemedium include, but are not limited to, a magnetic disk, an optical disc(e.g., CD, CD-R, DVD, DVD-R, etc.), a magneto-optical disk, a read-onlymemory “ROM” device, a random access memory “RAM” device, a magneticcard, an optical card, a solid-state memory device, an EPROM, an EEPROM,and any combinations thereof. A machine-readable medium, as used herein,is intended to include a single medium as well as a collection ofphysically separate media, such as, for example, a collection of compactdiscs or one or more hard disk drives in combination with a computermemory. As used herein, a machine-readable storage medium does notinclude transitory forms of signal transmission.

Such software may also include information (e.g., data) carried as adata signal on a data carrier, such as a carrier wave. For example,machine-executable information may be included as a data-carrying signalembodied in a data carrier in which the signal encodes a sequence ofinstruction, or portion thereof, for execution by a machine (e.g., acomputing device) and any related information (e.g., data structures anddata) that causes the machine to perform any one of the methodologiesand/or embodiments described herein.

Examples of a computing device include, but are not limited to, a laptopcomputer, a computer workstation, a terminal computer, a servercomputer, a handheld device (e.g., a tablet computer, a smartphone,etc.), a web appliance, a network router, a network switch, a networkbridge, any machine capable of executing a sequence of instructions thatspecify an action to be taken by that machine, and any combinationsthereof In one example, a computing device may include and/or beincluded in a kiosk.

FIG. 8 shows a diagrammatic representation of one embodiment of acomputing device in the exemplary form of a computer system 800 withinwhich a set of instructions for performing any one or more of theaspects and/or methodologies of the present disclosure may be executed.It is also contemplated that multiple computing devices may be utilizedto implement a specially configured set of instructions for causing oneor more of the devices to contain and/or perform any one or more of theaspects and/or methodologies of the present disclosure. Computer system800 includes a processor 804 and a memory 808 that communicate with eachother, and with other components, via a bus 812. Bus 812 may include anyof several types of bus structures including, but not limited to, amemory bus, a memory controller, a peripheral bus, a local bus, and anycombinations thereof, using any of a variety of bus architectures.

Memory 808 may include various components (e.g., machine-readable media)including, but not limited to, a random access memory component, a readonly component, and any combinations thereof. In one example, a basicinput/output system 816 (BIOS), including basic routines that help totransfer information between elements within computer system 800, suchas during start-up, may be stored in memory 808. Memory 808 may alsoinclude (e.g., stored on one or more machine-readable media)instructions (e.g., software) 820 embodying any one or more of theaspects and/or methodologies of the present disclosure. In anotherexample, memory 808 may further include any number of program modulesincluding, but not limited to, an operating system, one or moreapplication programs, other program modules, program data, and anycombinations thereof.

Computer system 800 may also include a storage device 824. Examples of astorage device (e.g., storage device 824) include, but are not limitedto, a hard disk drive, a magnetic disk drive, an optical disc drive incombination with an optical medium, a solid-state memory device, and anycombinations thereof. Storage device 824 may be connected to bus 812 byan appropriate interface (not shown). Example interfaces include, butare not limited to, SCSI, advanced technology attachment (ATA), serialATA, universal serial bus (USB), IEEE 1394 (FIREWIRE), and anycombinations thereof. In one example, storage device 824 (or one or morecomponents thereof) may be removably interfaced with computer system 800(e.g., via an external port connector (not shown)). Particularly,storage device 824 and an associated machine-readable medium 828 mayprovide nonvolatile and/or volatile storage of machine-readableinstructions, data structures, program modules, and/or other data forcomputer system 800. In one example, software 820 may reside, completelyor partially, within machine-readable medium 828. In another example,software 820 may reside, completely or partially, within processor 804.

Computer system 800 may also include an input device 832. In oneexample, a user of computer system 800 may enter commands and/or otherinformation into computer system 800 via input device 832. Examples ofan input device 832 include, but are not limited to, an alpha-numericinput device (e.g., a keyboard), a pointing device, a joystick, agamepad, an audio input device (e.g., a microphone, a voice responsesystem, etc.), a cursor control device (e.g., a mouse), a touchpad, anoptical scanner, a video capture device (e.g., a still camera, a videocamera), a touchscreen, and any combinations thereof. Input device 832may be interfaced to bus 812 via any of a variety of interfaces (notshown) including, but not limited to, a serial interface, a parallelinterface, a game port, a USB interface, a FIREWIRE interface, a directinterface to bus 812, and any combinations thereof. Input device 832 mayinclude a touch screen interface that may be a part of or separate fromdisplay 836, discussed further below. Input device 832 may be utilizedas a user selection device for selecting one or more graphicalrepresentations in a graphical interface as described above.

A user may also input commands and/or other information to computersystem 800 via storage device 824 (e.g., a removable disk drive, a flashdrive, etc.) and/or network interface device 840. A network interfacedevice, such as network interface device 840, may be utilized forconnecting computer system 800 to one or more of a variety of networks,such as network 844, and one or more remote devices 848 connectedthereto. Examples of a network interface device include, but are notlimited to, a network interface card (e.g., a mobile network interfacecard, a LAN card), a modem, and any combination thereof. Examples of anetwork include, but are not limited to, a wide area network (e.g., theInternet, an enterprise network), a local area network (e.g., a networkassociated with an office, a building, a campus or other relativelysmall geographic space), a telephone network, a data network associatedwith a telephone/voice provider (e.g., a mobile communications providerdata and/or voice network), a direct connection between two computingdevices, and any combinations thereof. A network, such as network 844,may employ a wired and/or a wireless mode of communication. In general,any network topology may be used. Information (e.g., data, software 820,etc.) may be communicated to and/or from computer system 800 via networkinterface device 840.

Computer system 800 may further include a video display adapter 852 forcommunicating a displayable image to a display device, such as displaydevice 836. Examples of a display device include, but are not limitedto, a liquid crystal display (LCD), a cathode ray tube (CRT), a plasmadisplay, a light emitting diode (LED) display, and any combinationsthereof. Display adapter 852 and display device 836 may be utilized incombination with processor 804 to provide graphical representations ofaspects of the present disclosure. In addition to a display device,computer system 800 may include one or more other peripheral outputdevices including, but not limited to, an audio speaker, a printer, andany combinations thereof. Such peripheral output devices may beconnected to bus 812 via a peripheral interface 856. Examples of aperipheral interface include, but are not limited to, a serial port, aUSB connection, a FIREWIRE connection, a parallel connection, and anycombinations thereof.

The foregoing has been a detailed description of illustrativeembodiments of the disclosure. It is noted that in the presentspecification and claims appended hereto, conjunctive language such asis used in the phrases “at least one of X, Y and Z” and “one or more ofX, Y, and Z,” unless specifically stated or indicated otherwise, shallbe taken to mean that each item in the conjunctive list can be presentin any number exclusive of every other item in the list or in any numberin combination with any or all other item(s) in the conjunctive list,each of which may also be present in any number. Applying this generalrule, the conjunctive phrases in the foregoing examples in which theconjunctive list consists of X, Y, and Z shall each encompass: one ormore of X; one or more of Y; one or more of Z; one or more of X and oneor more of Y; one or more of Y and one or more of Z; one or more of Xand one or more of Z; and one or more of X, one or more of Y and one ormore of Z.

Various modifications and additions can be made without departing fromthe spirit and scope of this disclosure. Features of each of the variousembodiments described above may be combined with features of otherdescribed embodiments as appropriate in order to provide a multiplicityof feature combinations in associated new embodiments. Furthermore,while the foregoing describes a number of separate embodiments, what hasbeen described herein is merely illustrative of the application of theprinciples of the present disclosure. Additionally, although particularmethods herein may be illustrated and/or described as being performed ina specific order, the ordering is highly variable within ordinary skillto achieve aspects of the present disclosure. Accordingly, thisdescription is meant to be taken only by way of example, and not tootherwise limit the scope of this disclosure.

Example embodiments have been disclosed above and illustrated in theaccompanying drawings. It will be understood by those skilled in the artthat various changes, omissions and additions may be made to that whichis specifically disclosed herein without departing from the spirit andscope of the present disclosure.

What is claimed is:
 1. A method of fitting an electrical transformerwith a fault indicator that indicates when the electrical transformerhas experienced a fault that causes an internal pressure increase withinan interior space of the electrical transformer, wherein the electricaltransformer has a preexisting pressure-relief-valve port designed andconfigured to receive a conventional pressure-relief valve, the methodcomprising: providing a fault-indicator assembly comprising: apressure-relieve valve; a pressure-activated actuator operativelycoupled to an onboard visual indicator or a communication trigger, orboth an onboard visual indicator and a communication trigger, whereinthe fault-indicator assembly is provided to sense when the internalpressure has increased in a manner characteristic of a fault occurringwith the electrical transformer; and a fitting designed and configuredto engage the preexisting pressure-relief-valve port; and securing thefault-indicator assembly to the electrical transformer, wherein thesecuring includes engaging the fitting of the fault-indicator assemblywith the preexisting pressure-relief-valve port.
 2. The method of claim1, wherein the conventional pressure-relief valve is initially engagedwith the preexisting pressure-relief-valve port, and the method furthercomprises, prior to engaging the fitting of the fault-indicator assemblywith the preexisting pressure-relief-valve port, disengaging theconventional pressure-relief valve from the preexistingpressure-relief-valve port.
 3. The method of claim 2, wherein theelectrical transformer is a transformer already deployed for use, andthe method is a method of retrofitting the electrical transformer withthe fault-indicator assembly.
 4. The method of claim 1, wherein thepreexisting pressure-relief-valve port is a threaded port, and thefitting is threaded to threadingly engage the threaded port.
 5. Themethod of claim 1, wherein the electrical transformer has an exteriorsidewall, and the preexisting pressure-relief-valve port is in theexterior sidewall.
 6. The method of claim 1, wherein the preexistingpressure-relief-valve port defines an opening having a central axis, andthe pressure-relief valve and the fitting lie along the central axis. 7.The method of claim 6, wherein the onboard visual indicator extends awayfrom the central axis.
 8. The method of claim 7, wherein the onboardvisual indicator extends radially away from the central axis.
 9. Themethod of claim 1, wherein the pressure-activated actuator is fluidlyconnected to the fitting fluidly upstream of the pressure-relief valve.10. The method of claim 1, wherein the onboard visual indicator ispresent and the communication trigger is not present.
 11. The method ofclaim 1, wherein the communication trigger is present and thefault-indicator assembly further includes a communication moduledesigned and configured to communicate a fault-notification signal overone or more networks.
 12. The method of claim 11, wherein thepressure-activated actuator comprises an electronic pressure sensor, andthe communication trigger comprises circuitry that generates and sends asignal to the communications module when the pressure equals the presetpressure.
 13. The method of claim 1, wherein: the onboard visualindicator is present; and the communication trigger is present and thefault-indicator assembly further includes a communication moduledesigned and configured to communicate a fault-notification signal overone or more networks.
 14. The method of claim 1, wherein thepressure-activated actuator comprises a deformable component thatdeforms with changing pressure within the interior space of theelectronic device.
 15. The method of claim 14, wherein the deformablecomponent comprises a bellows.
 16. The method of claim 1, wherein theelectrical transformer has a sidewall and, when the fault-indicatorassembly is secured to the electrical transformer, longitudinal axes ofthe fitting and the pressure-relieve valve are colinear andperpendicular to the sidewall, and the pressure-activated actuatorextends away from the longitudinal axes of the fitting and thepressure-relief valve.
 17. The method claim 1, wherein the onboardvisual indicator is present and is movable between anon-fault-indicating position and a fault-indicating position and thefault-indicator assembly further comprises: a catch operatively engagedwith the onboard visual indicator, the catch maintaining the onboardvisual indicator in the non-fault-indicating position until triggered torelease the onboard visual indicator; and a trigger responsive to thepressure-activated actuator and operatively engaged with the catch so asto release the catch in response to the trigger being triggered by thepressure-activated actuator.
 18. The method of claim 17, wherein theonboard visual indicator comprises an elongate body slidable within amating receiver along a longitudinal axis between thenon-fault-indicating position and the fault-indicating position.
 19. Themethod of claim 18, further comprising a biasing means that biases theelongate body toward the fault-indicating position.
 20. The method ofclaim 1, wherein the pressure-relief valve is configured to releasepressure at a first pressure magnitude, the fault-indicator assemblybeing designed and configured with an adjustable pressure setpoint,wherein, when the adjustable pressure setpoint is set at a magnitudebelow the first pressure magnitude, the fault-indicator assemblyprovides a pressure indication that is independent of a rate of increaseof the interior space pressure, and, when the adjustable pressuresetpoint is set at a magnitude above the first pressure magnitude, thefault indicator assembly provides a pressure indication that isdependent on a rate of increase of the interior space pressure.
 21. Themethod of claim 1, wherein the fault-indicator assembly has anadjustable pressure setpoint that provides a pressure measurement thatis selectively configurable as dependent or independent of a rate ofincrease of the interior space pressure.
 22. The method of claim 1,wherein the pressure-activated actuator is configured to detect slow andaccumulative pressure increases.
 23. The method of claim 1, wherein theonboard visual indicator is present, and the pressure-activated actuatoris configured to cause the onboard visual indicator to change to afault-indicating state in response to a magnitude of pressure within theinterior space of the electrical transformer equaling a preset pressureindependently of a rate of increase of the pressure within the interiorspace of the electrical transformer.